Agree completely with Blake. Another caveat- calories in vs. calories out, but you still need enough protein. So, understand that if you eat a pint of ice cream, you'll have to eat low-carb and low-fat the rest of the day. Further, a loose diet will help you lean out, but in order to break that threshold into insane ripped-ness (something most people don't even want) you have to really clean it up.
Agreed. Protein becomes more important in hypocaloric situations.
And I also agree that the lower you get wrt bodyfat levels, the more strict you'll have to be with eating and cardio to continue making progress.